Canadian Patents Database / Patent 2958456 Summary

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(12) Patent Application: (11) CA 2958456
(54) English Title: METHOD AND APPARATUS FOR LOAD BALANCING TRAPPED SOLAR ENERGY
(54) French Title: METHODE ET APPAREIL D'EQUILIBRAGE DE CHARGE D'ENERGIE SOLAIRE PIEGEE

English Abstract


A method and apparatus for load balancing trapped solar energy using small
masses of
low-boiling-point fluids to absorb heat in an evaporator situated in higher
heat reservoir
near the ocean surface using the latent heat of evaporation to convert a
portion of the heat
to another form of energy in a turbine or other heat engine, providing a
variety of energy
related service applications to end users from the converted energy,
depositing a residual
latent heat of evaporation in a deep ocean heat exchanger situated in the
lower heat
reservoir, using the cold seawater as a heat sink. A latent heat of
condensation warms the
cold seawater making it buoyant. The warmed water rises slowly by convection
to the
higher heat reservoir where the heat is recycled in a turbine or other heat
engine. The
condensed liquid is pumped rapidly back to the ocean surface to complete the
fluid cycle.


Note: Claims are shown in the official language in which they were submitted.

Claims
What is claimed is:
1. A method and apparatus for transferring heat from near the ocean surface to
a location
far below the ocean surface, comprising: a heat exchanger evaporator near the
ocean
surface, which uses warm ocean water to provide heat for evaporating a low-
boiling-
point liquid to produce a vapor; and a conduit for conducting the vapor to a
location far
below the ocean surface; and a heat exchanger condenser at the location far
below the
ocean surface for the purpose of condensing the vapor back to a liquid; and a
pump and
pipe for moving the condensed liquid back to the heat exchanger evaporator
near the
surface of the ocean; wherein heat absorbed from warm ocean water by the heat
exchanger evaporator causes the evaporation of the low boiling point liquid
for the
purpose of absorbing the latent heat of evaporation as it produces a vapor,
and wherein
the vapor is transported to the heat exchanger condenser where it condenses to
a liquid as
it releases the latent heat of condensation, wherein the latent heat of
condensation warms
the ocean far below the ocean surface, wherein warmed water far below the
ocean surface
is returned to the ocean surface by convection, and wherein the liquid is
pumped by the
pump and through the pipe back to the heat exchanger evaporator.
2. A method and apparatus according to claim 1, wherein the vapor that flows
from the
heat exchanger evaporator to the location far below the ocean surface
transfers the heat to
the heat exchanger condenser and wherein the latent heat of condensation warms
the
ocean far below the ocean surface, wherein the warmed water far below the
ocean surface
is returned to the ocean surface by convection, and wherein the warmed water
from
below the ocean surface again enters the heat exchange evaporator.
3. A method and apparatus according to claim 1, wherein the vapor that flows
from the
heat exchanger evaporator is used to boil a working fluid that is used to
drive a turbine or

other heat engine and wherein the exhaust from the turbine or other heat
engine is
condensed in a heat exchanger that is cooled by cold deep ocean seawater, and
wherein
the condensed working fluid is pumped by a feed pump back into the heat
exchanger
condenser to be boiled again.
4. A method and apparatus according to claim 1, wherein the vapor that flows
from the
heat exchanger evaporator through a turbine or other heat engine, and wherein
the turbine
or other heat engine produces work, and wherein the works provides a variety
of energy
related service applications to end users.
5. A method and apparatus according to claim 1, wherein the vapor that flows
from the
heat exchanger evaporator to the location far below the ocean surface flows
through a
turbine or other heat engine on the way to the heat exchanger condenser, and
wherein the
vapor is condensed to a liquid in the heat exchanger condenser by the cold
ocean water,
and the liquid pumped back to the heat exchanger evaporator near the ocean
surface.
6. A method and apparatus according to claim 1; wherein heat is absorbed more
rapidly
near the ocean surface than below far below the ocean; wherein movement of
heat from
near the ocean surface to far below the ocean balances the thermal load taken
up by the
ocean.
7. A method and apparatus according to claim 1; wherein heat from near the
ocean is
reduced by conversion of a portion of the heat to work in a heat engine.
8. A method and apparatus according to claim 1; wherein warmed water far below
the
ocean surface is returned to the ocean surface by convection and wherein the
warmed
water at the ocean surface is recycled in a heat engine.
9. A method and apparatus for transferring heat from the ocean surface to a
location far
below the ocean surface, comprising: a conduit for conducting exhaust vapor
consisting
of a low-boiling-point fluid from a turbine or other heat engine or from a
desalination
unit near the surface of the ocean to a location far below the ocean surface;
and a heat
exchanger condenser far below the surface of the ocean for the purpose of
condensing the
vapor to a liquid; and a heat exchanger boiler near the surface of the ocean
for the
purpose of transferring heat from the warm surface seawater to heat and
evaporate the
liquid; and a pipe to conduct the heated and evaporated vapor from the heat
exchanger
boiler to the turbine or other heat engine or to the desalination plant; and a
pump and a
second pipe for moving the condensed liquid from the heat exchanger condenser
through
a pipe to the heat exchanger boiler near the surface of the ocean for the
purpose of
heating and re-evaporating the liquid; wherein warm ocean surface water is
used to heat
and evaporate the low-boiling-point fluid to produce a vapor in the heat
exchanger boiler,
which vapor is conducted to the turbine or other heat engine or to the
desalination of
seawater, and wherein the exhaust vapor from the turbine or other heat
exchanger or
desalination plant is conducted by the conduit to a location far below the
ocean surface to
be condensed in the heat exchanger condenser, which deposits the heat of
condensation
of the vapor into the cold seawater, wherein the heat transferred far below
the ocean

surface returns to the ocean surface by convection and wherein the condensed
liquid is
pumped by the pump and the second pipe back to the heat exchanger boiler at
the surface
of the ocean.
BACKGROUND OF THE INVENTION
The average global temperature on Earth has increased by about 0.8°
Celsius since 1880.
Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-
0.20°C per
decade. Since 1955, over 90% of the excess heat that has been trapped by
greenhouse
gases has been stored in the oceans. About 60% of this heat has been taken up
in the
upper 700 meters, while 30% is stored in deeper layers. The largest changes in
ocean
temperatures have been observed in the upper 75 meters of the ocean, due to
closer
proximity to the atmosphere and the large mixing within this layer. Ocean
currents move
vast amounts of heat across the planet - roughly the same amount as the
atmosphere does.
But in contrast to the atmosphere, the oceans are confined by land masses, so
that their
heat transport is more localised and channelled into specific regions.
Temperature gains
are larger at the sea surface, which heats faster than the ocean as a whole.
The top 75
meters have warmed an average of .01 degrees Celsius per year since 1971
whereas
between 500 to 2000 meters, oceans are warming by about .002 degrees a year.
The heat
at the surface is demonstrably more damaging than heat in the abyss, below 700
meters,
because amongst other things there is at least 5 times much of it. At the
surface
increasing heat due to global warming intensifies the hydrological cycle.
Increased
surface air temperature causes an increase in evaporation and generally higher
levels of
water vapor in the atmosphere. In addition, a warmer atmosphere is capable of
holding
more water vapor. The excess water vapor will in turn lead to more frequent
heavy
precipitation when atmospheric instability is sufficient to trigger
precipitation events
whereas other regions are experiencing drought and the expansion of dry areas.
Sea level rise is one of the primary concerns of global warming and is driven
by thermal
expansion of the oceans, the melting of glaciers and polar ice caps and ice
loss from
Greenland and West Antarctica.
Stacked against these surface environmental concerns are the potential of
115th as much
heat impacting marine below 700 meters where photosynthesis is absent, the
water is
cold, pressures is great, food is scarce and biodiversity is scarce and a
study suggesting
extreme, at least 1000 times background, ocean thermal mixing and hence
surface ocean
cooling, would produce net global warming after 60 years primarily due to loss
of clouds
and ice cover and hence gain in planetary albedo as well the scientific fact
that the
thermal coefficient of expansion of sea water at a depth of 1000 meters is
about half it is
at the ocean surface.
It has to be noted that with a business as usual scenario global average
temperatures
could increase to about 4°C in 60 years and the temperature in the
abyss would therefore
be about .4°C warmer than the present.

Note: Descriptions are shown in the official language in which they were submitted.

CA 02958456 2017-02-21
surface returns to the ocean surface by convection and wherein the condensed
liquid is
pumped by the pump and the second pipe back to the heat exchanger boiler at
the surface
of the ocean.
BACKGROUND OF THE INVENTION
The average global temperature on Earth has increased by about 0.8 Celsius
since 1880.
Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-
0.20 C per
decade. Since 1955, over 90% of the excess heat that has been trapped by
greenhouse
gases has been stored in the oceans. About 60% of this heat has been taken up
in the
upper 700 meters, while 30% is stored in deeper layers. The largest changes in
ocean
temperatures have been observed in the upper 75 meters of the ocean, due to
closer
proximity to the atmosphere and the large mixing within this layer. Ocean
currents move
vast amounts of heat across the planet - roughly the same amount as the
atmosphere does.
But in contrast to the atmosphere, the oceans are confined by land masses, so
that their
heat transport is more localised and channelled into specific regions.
Temperature gains
are larger at the sea surface, which heats faster than the ocean as a whole.
The top 75
meters have warmed an average of .01 degrees Celsius per year since 1971
whereas
between 500 to 2000 meters, oceans are warming by about .002 degrees a year.
The heat
at the surface is demonstrably more damaging than heat in the abyss, below 700
meters,
because amongst other things there is at least 5 times much of it. At the
surface
increasing heat due to global warming intensifies the hydrological cycle.
Increased
surface air temperature causes an increase in evaporation and generally higher
levels of
water vapor in the atmosphere. In addition, a warmer atmosphere is capable of
holding
more water vapor. The excess water vapor will in turn lead to more frequent
heavy
precipitation when atmospheric instability is sufficient to trigger
precipitation events
whereas other regions are experiencing drought and the expansion of dry areas.
Sea level rise is one of the primary concerns of global warming and is driven
by thermal
expansion of the oceans, the melting of glaciers and polar ice caps and ice
loss from
Greenland and West Antarctica.
Stacked against these surface environmental concerns are the potential of
1/5th as much
heat impacting marine below 700 meters where photosynthesis is absent, the
water is
cold, pressures is great, food is scarce and biodiversity is scarce and a
study suggesting
extreme, at least 1000 times background, ocean thermal mixing and hence
surface ocean
cooling, would produce net global warming after 60 years primarily due to loss
of clouds
and ice cover and hence gain in planetary albedo as well the scientific fact
that the
thermal coefficient of expansion of sea water at a depth of 1000 meters is
about half it is
at the ocean surface.
It has to be noted that with a business as usual scenario global average
temperatures
could increase to about 4 C in 60'years and the temperature in the abyss would
therefore
be about .4 C warmer than the present.

CA 02958456 2017-02-21
Using the temperature differential between the surface of the tropical ocean
and the water
1,000 metres below is an important way to provide abundant electrical power.
Ocean
Thermal Energy Conversion (OTEC) uses the warm surface water to boil a working

liquid to produce a vapor that drives a turbine, and it pumps cold water from
the dark
depths to the surface to condense the vapor after it leaves the turbine. A 100
MW OTEC
plant would require 200 cubic meters of cold water per second flowing up
through a 11
meter (36 foot) diameter pipe. Since the cold water is denser than the
surrounding water,
just lifting the extra weight of the water would require about 3.5 MW of
power. The
resistance to the flow due to the viscosity of the water would require 20 to
30 additional
MW of pumping power.
Another problem with this method of transporting heat is that only a portion
of the heat is
delivered once the masses of water reach their destination. Even though there
is a 23 C.
temperature differential, the cold water temperature rises by about only 6
once it reaches
the plant heat exchangers. The rest of the "coldness" is thrown away.
US. Pat. No. 4,104,883 provides a method of transferring heat for an OTEC
plant by
using phase change methods. Somewhat related to the present invention is US.
Pat. No.
4,324,983.
SUMMARY OF THE INVENTION
The ocean's surface heat load is balanced by moving heat excess to mankind's
energy
needs, that may be environmentally damaging, to deep water.
The diffusion rate of ocean water is generally estimated at 1.2
centimetres/day or about of
4 meters/year.
Rather than moving large quantities of cold water from the depths, this
invention
provides a method that moves heat by the most economical method possible while

leaving the water where it is and where heat is relocated to deep water where
it has less
environmental impact than at the surface.
It uses a long "heat pipe" for transporting energy over a distance of about
1000 meters. A
heat pipe is a long tube that uses vapor to transfer large amounts of heat.
When the vapor
gets to the cool end, it condenses and releases its heat. Normally, heat pipes
have an
interior wick that moves the condensed liquid back to the hot end. Since it
would not be
practical to have a wick transport the liquid for a kilometer of vertical
distance, the heat
pipe described herein will pump the liquid to the surface. Since it is
different than the
standard heat pipe, we may call it a "heat channel."
In about 250 years, at a return of 4 meters/year, when it is anticipated that
the atmosphere
will no longer be accumulating greenhouse gases and thus increasing the
atmospheric
heat load, heat that has been moved to deep water by the invention will be
return to the
ocean surface through diffusion where it can be recycled through the heat
engine once
again to produce additional work.

CA 02958456 2017-02-21
The efficiency of a thermodynamic cycle using temperature differences between
277 and
297 degrees Kelvin is about 7 percent. In practical terms it is somewhere
between 3 and 5
percent so with every cycle of heat movement from the surface through a heat
engine to
the abyss about 4 percent of the heat is converted to work. In about 6,250
years, by
recycling the energy of global warming 25 times over, all of the heat that has
been
accumulated due to global warming by the time we stop contributing additional
greenhouse gases will have been converted to productive use and the excess
heat load
accumulated by the ocean surface due to global warming will have been
levelled.
The heat channel forms a conduit for conducting a low-boiling-point fluid
vapor from the
top to the bottom of the system. An evaporation chamber at the top of the heat
channel
absorbs heat and uses that heat to vaporize the fluid. The vapor then flows
down the pipe
to the bottom, where it condenses and releases large quantities of heat. The
condensed
liquid is then pumped back up to the top, where it re-enters the evaporation
chamber to
repeat the process.
It is therefore an object of the present invention to provide a means of
moving large
quantities of heat from the ocean surface to cold water deep in the ocean by
using
evaporation of a fluid, conducting the fluid from the ocean surface to deep
ocean, and
condensing the fluid.
It is another object of the present invention to balance the solar energy load
of global
warming between the ocean surface and the deep ocean.
It is another object of the present invention to provide a means of moving
large quantities
of heat from the top of an OTEC plant to the location of cold water deep in
the ocean by
using evaporation of a fluid, conducting the fluid from the ocean surface to
deep ocean,
and condensing the fluid.
It is another object of the present invention is to increase the efficiency of
an OTEC plant
by its method of transferring heat in heat exchangers at constant
temperatures.
It is another object of the present invention to eliminate the energy
requirements of
pumping large quantities of cold seawater to the surface.
It is another object of the present invention to provide a means of utilizing
natural deep
ocean currents or convection currents to force the cold seawater through the
heat
exchanger in deep ocean.
It is another object of the present invention to extract the maximum work
potential from
the heat trapped by global warming.
Other objects, advantages and novel features, and further scope of
applicability of the
present invention will be set forth in part in the detailed description to
follow, taken in
conjunction with the accompanying drawings, and in part will become apparent
to those

CA 02958456 2017-02-21
skilled in the art upon examination of the following, or may be learned by
practice of the
invention. The objects and advantages of the invention may be realized and
attained by
means of the instrumentalities and combinations particularly pointed out in
the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated into and form a part of the
specification, illustrate embodiments of the present invention and, together
with the
description, serve to explain the principles of the invention. The drawings
are only for the
purpose of illustrating preferred embodiments of the invention and are not to
be
construed as limiting the invention. In the drawings:
FIGURE1 is a schematic cross-sectional view of classic thermohaline
circulation of the
Northern hemisphere.
FIGURE 2 is a schematic cross-sectional view of thermohaline circulation of
the
Northern and Southern hemispheres.
FIGURE 3 is an isometric projection of the regions of the ocean where ocean
heat
transfers back to the atmosphere.
FIGURE 4 is a schematic view of the Earth's surface and the regions where
energy can
be produced by the relocation of surface heat to deep ocean.
FIGURE 5 is a schematic side view drawing of an Ocean Power System plant that
uses a
long heat channel to conduct a heat transfer vapor from the ocean surface to a
boiler that
boils a working fluid at deep point in the ocean. The working fluid drives a
turbine and is
condensed in a cold water condenser.
FIGURE 6 is a schematic side view of a simpler method in which the turbine
working
fluid and the heat transfer fluid are the same.
FIGURE 7 is a schematic side view of an embodiment of an Ocean Power System
that
has the boiler and turbine near the surface of the ocean and has the condenser
at deep
ocean.
FIGURE 8 is a schematic of the Earth's surface and the regions of the ocean
gyres.
DETAILED DESCRIPTION OF THE INVENTION
Let us consider the thermohaline circulation of the Northern Hemisphere.
FIGURE 1
gives a schematic cross-sectional view of the thermohaline circulation 10.
Solar radiation
11 impacts the ocean surface 12 near the equator 13 creating a zone of heating
14. Solar
radiation produces heat 15 that flows from the equator 13 along the ocean
surface 12
towards the North Pole 16 where out going longwave radiation 17 is emitted
from the top

CA 02958456 2017-02-21
of the atmosphere 18 back into space 19. Around the 45th parallel 20 the zone
of heating
14 transitions to a zone of cooling 21 as the intensity of solar radiation 11
decreases as
represented by the diminishing, black, down going heat arrows 15 and above the
45th the
growing gray arrows 17 represent the longwave radiation releasing heat 15 back
into
space 19. Ocean water 22 flows from the equator 13 towards the North Pole 16
along the
ocean surface 12 loosing heat 15 as it cools. Near the North Pole 16, ocean
water 22
freezes in the winter months and in that process it looses salt 23 that sinks
towards the
ocean floor 24 under the influence of gravity 26. Fifteen million cubic meters
of near
surface cold ocean water 22 sinks into the deep ocean to the ocean floor 24
each year and
this sinking 25 is the driver for the thermohaline circulation 10. In mid
ocean the sinking
water pushes out a zone of deep spreading bottom water 27 and as the spreading

continues towards the equator 13 the now warming water begins rising 28 under
the
influence of buoyancy 29. The thermocline 30 is the ocean layer in which water

temperature decreases rapidly with increasing depth and exists beneath the
relatively
warm, well-mixed surface layer 31, from depths of about 200 meters to about
1,000
meters.
FIGURE 2 is a schematic cross-sectional view of thermohaline circulation 10
which is a
part of the large-scale ocean circulation that is driven by global density
gradients created
by surface heat and freshwater fluxes. Surface water 35 is warmed in the
vicinity of the
equator 13 and moves towards the North Pole 16 where it sinks to produce North

American deep water (NADW) 36 which is a deep water mass formed in the North
Atlantic Ocean with temperatures of between 2-4 C. Antarctic bottom water
(AABW)
37 is a mass of ocean water in the Southern Ocean surrounding Antarctica with
temperatures ranging from ¨0.8 to 2 C produced by the sinking and spreading
of cold
water along the ocean floor 24. The schematic shows the movement of heat 15 on
the
periphery of the ocean 39. In intermediate water 40 heat 15 returns to the
ocean surface
12 by diffusion; at a rate of about 4 meters/year and is cooled by the
diffusion from the
cold deeper waters of the NADW and the AABW below.
FIGURE 3 is an isometric projection of the regions of the ocean showing the
thermohaline circulation 10 where cold and salty deep current 41 transfers
heat to the
atmosphere 18 and warm shallow current 42 circulates about the ocean surface
12. At the
surface heat can transfer from the ocean to the atmosphere and can migrate
rapidly
towards the poles which are warming more rapidly than the rest of the planet.
FIGURE 4 is a map of the world showing the regions of the ocean best suited to
ocean
thermal energy conversion. The greatest efficiency and power for OTEC
conversion is
derived where the greatest temperature differences exist between the surface
temperature
and the deep ocean water. The warmest ocean surface waters 46 are 24 C and
above in
the Pacific Ocean 47 west of Indonesia and the Philippines. Surface
temperatures in the
range of 22 C - 24 C 48 are found in the equatorial regions of the Eastern
Pacific, the
Atlantic 49 and the Indian Oceans 50. And temperatures of 20 C - 22 C 51 are
found in
the Western Pacific and more northerly and southerly reaches of the Atlantic
49. A
temperature difference of at least 20 C between the ocean surface and the
deep ocean at
a depth 1000 meters where the ocean temperatures is universally about 4 C is
required to

CA 02958456 2017-02-21
produce energy from an OTEC system. A portion of the energy produced by the
OTEC
system is required to relocate surface heat to deep water with this invention.
FIGURE 5 gives a schematic presentation of a design for an OTEC system in
which the
turbines, generators, and heat exchangers are at 1,000-meter depth. At the
ocean surface
12, warm seawater 55 entering pipe 56 is pumped through a heat exchanger or
simply
moved across a heat exchange surface 57 on the bottom of an evaporation tank
58 that
transfers heat into a heat transfer liquid 60 that evaporates and carries the
latent heat of
evaporation down the heat channel 61 to a depth of 1,000-meters. It should be
understood
that the heat transfer can be done with a heat exchanger that has many heat
transfer
surfaces. The drawing of FIGURE 5 presents the concept with a single surface
for
simplicity.
At the bottom, the vapor condenses on a heat exchange surface 62 (or in a heat

exchanger) and transfers heat into a working fluid in a boiler 63, and the
working fluid
drives a turbine 64 to produce electricity.
The exhaust from the turbine is condensed in a heat exchanger 65 by cold
seawater,
which enters by pipe 66 and is exhausted by pipe 67. Since the cold seawater
is nearby
larger quantities can be used so that the temperature rise is smaller, and the
condensing
temperature of the turbine exhaust can be lower, and the efficiency will be
higher.
Similarly, at the ocean surface, the warm water is nearby, so that larger
quantities can be
used to supply the heat. The warm seawater, after delivering its heat to the
evaporation
tank is exhausted through pipe 58.
Since the viscosities and densities of vapors are much less than liquids, the
velocities of
the heat being transported in the heat channel 61 can be much higher than that
of the cold
water that would be pumped in ordinary OTEC plants. Since latent heats of
evaporation
and condensation are much greater than the heat capacity of water for the same
mass,
much less mass needs to be transferred.
The turbine working fluid liquid flows from the heat exchanger 65 via boiler
feed pump
68 back to the boiler 63.
The condensed transfer fluid is pumped back by pump 69 via pipe 70 to the
evaporation
tank 59 at the ocean surface.
This type of power generating plant can be called an "Ocean Power System"
(OPS).
The heat channel pipe needs to be strong steel to sustain the ocean pressure
at depth.
However, there must be excellent thermal insulation between the ocean and the
transfer
fluid vapor. The pipe should have a lighter insert pipe that may have an
evacuated half-
inch gap between it and the outer pipe. The inside of the main pipe and the
outside of the
insert should be highly reflective to reduce radiative heat loss. The buoyancy
of the pipe
should be matched by the weight of the pipe so that it would not be necessary
to provide
strong support for the pipe from above or to anchor it by cables from below.
For a pipe

CA 02958456 2017-02-21
with an internal cross sectional area of one square meter, a steel pipe would
need to have
a thickness of 4.05 cm (1.59 inches) to meet this criterion. That would
probably provide
sufficient strength so sustain the water pressure. If necessary, the pipe can
be thin near
the top and be thicker near the bottom.
A transfer fluid, like carbon dioxide, operating within the OTEC temperature
range,
would exert about half the internal pressure on the heat channel as the
external water
pressure being exerted on it therefore the thickness of the pipe could be
reduced by using
carbon dioxide as the transfer fluid.
The transfer fluid can be a liquid that has a fairly low boiling point. With
an inside
diameter of 1.128 meter (cross sectional area of 1 m2) a vapor velocity of 75
meters per
second could transfer heat from the ocean surface to a depth of 1000 meters in
about 14
seconds.
On account of global warming the world oceans are storing more heat than they
are
giving up. A 2010 NOAA study estimated the upper layer of the world's ocean
are
storing enough excess heat to power nearly 500 100-watt light bulbs per each
of the
roughly 6.7 billion people on the planet, which amounts to about 330 terawatts
(TW) of
energy.
It has been estimated that the oceans have a worldwide potential to produce
about 14 TW
of electrical energy and at an efficiency rate of about 4%, these plants could
move all of
the excess heat being stored by global warming into the thermocline 30 to a
depth 1000
meters where it is not available to melt polar icecaps. Between 2003 ¨ 2007
between 75 ¨
80 percent of the measured sealevel rise was attributed to glacier melt.
Table 1 from "The Oceans Their Physics, Chemistry, and General Biology" by H.
U.
Sverdrup, Director, Scripps Institution of Oceanography, shows that heat at
2000 decibars
(2000 meters), and at a temperature of 5 C has a coefficient of thermal
expansion of 157
e X 106 compared to a coefficient of thermal expansion of 297 e X 106 for
water at the
surface, 0 decibars, at a temperature of 25 C. Temperatures of 5 to 25 C are
the range
of operating temperatures of OTEC therefore heat at a depth of 1000 meters,
where ocean
water is at its maximum density, at a temperature of 4 C, has half the sea
level impact of
surface ocean water at a temperature 25 C therefore it is beneficial for sea
level rise to
move warm surface water 35 into the thermocline 30 with this invention.
TABLE I
COEFFICIENT OF THERMAL EXPANSION OF SEA WATER AT DIFFERENT TEMPERATURES,
SALINITIES, AND PRESSURES (e x 106)
Pressure Salinity Temperature ( C)
(decibars) /00.
¨2 0 5 10 15 20 25 30
0 35 23 51 114
167 214 257 297 334
2,000 35 80 105 157 202 241 278
4,000 35 132 152 196 233 266

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6,000 34.85 177 194 230
8,000 34.85 231 246
10,000 34.85 276 287
Table II was compiled by a program "Otec.exe," which numerically follows vapor
from
the top to the bottom of a long pipe to a depth of 1000 meters where: "Top
Pressure" and
"Top Density" mean the pressure and density of the vapor at the top of the
heat channel
as the vapor begins to flow downward. "Energy Delivered" means the amount of
energy
deposited in the boiler at the bottom of the pipe. "Plant Power" means the
theoretical
amount of power put out by the turbine. "Net Power" is the result of
subtracting the
Pump "Pump Power" means the amount of power required to pump the condensed
Power
from the Plant Power. "Net Efficiency" compares the Net Power to the heat
"Energy
Delivered" to the bottom of the heat channel.
TABLE II
Transfer Top Top Latent Energy Pressure Temperature Plant Pump Net Net
Fluid Pressure Density Heat Delivel ed At Bottom At Bottom
Power Power Power Efficiency
(bars (kg/m1) (kj/kg) (MW) (bai s) (degrees C) (MW)
(MW) MW) (%)
Ammonia 10.61 8.264 1158 717 11.43 32.3 59.4 4.66
54.7 7.6
Water 0.0353 0.0256 2438 4.674 0,0378 31.9 0.382 0.018
0.367 7.8
Acetone 0.318 0.707 533 28.26 0.3899 38.1 - 2.82
0.520 2.30 8.1
Propane 9.997 21.69 333 541 12.322 37.6 53.3 11.64
41.7 7.7
Methanol 0.20 0.263 1161 22.9 0.2272 33.5 1.97 0.194
1.78 7.8
Decane 0.0020 0.0113 360 0.305 0.00337 55.1 0.045 0.008
0.037 12.0
R 134A 8.0 38.99 272 795 12.67 50.9 107.7 26.3 81.4
10.2
Propylene 12.12 25.64 331 637 14.86 37.4 62.4 12.9
49.5 7.8
For this table, fluids were chosen to show a variety of different
characteristics. Note that
the temperature at the bottom of the heat channel pipe is hotter than the
initial
temperature (27 C.). That is because as the vapor flows downward, the weight
of the
vapor above it compresses it, increasing the temperature and the pressure.
Notice that for some of the fluids, there is considerable pressure at the
bottom of the heat
channel. That pressure assists in pumping the transfer liquid upward. This
effect was
included in the pump power calculations. In other liquids, the pressure
provides
insignificant lift.
The increase in temperature of the transfer vapor at the bottom is a
significant aspect of
the Ocean Power System. Whenever there is a heat engine that has a small
temperature
differential between the input and output temperatures, any small increase in
that
differential can dramatically improve the efficiency.
With conventional OTEC designs surface water surface temperatures of 27 C is
reduced
to about 23 C in the boiler, which is the temperature of the steam (or other
working

CA 02958456 2017-02-21
fluid) as it goes to the turbine. Even though the seawater is 4 C at 1000
meters, the
condenser operates at 10 C so the theoretical efficiency is 4.3% or (1-
2831Q296K).
Of course, both the standard OTEC plant and the OPS will operate below the
Carnot
efficiencies, but the theoretical efficiencies provide a guide to which real
system will
perform more efficiently.
We should examine the reasons for the differences in efficiencies. At the top
in the OPS
plant, the heat transfer fluid evaporates at constant temperature. Since this
heat is
supplied from nearby ocean water, large quantities of water can be used so
that there is a
small drop in temperature of the water. The heat transfer vapor increases in
temperature
as it flows downward and condenses at constant temperature as it boils the
working fluid
in the boiler at constant temperature. That is, the heat transfer into the
boiling working
fluid occurs at the high temperature point of the cycle, and this temperature
is higher than
the temperature of the ocean at the surface. If, instead of using the heat
channel, warm
water from the ocean surface were pumped down to the boiler, the temperature
of the
water would drop down several degrees during heat exchange, and the
temperature of the
boiler working fluid would be that of the lowest temperature of the seawater
from the
surface. This means that the efficiency will be less. The other problem is
that only a small
fraction of the heat energy transported in the water is actually used. With
the heat transfer
fluid in the heat channel, nearly all the transported energy is used.
After the working fluid vapor leaves the turbine, it is condensed by cold
seawater. If that
water had to be pumped up 1000 meters to a turbine at the ocean surface, it
would be a
precious commodity, and there would be a fairly large temperature change,
meaning that
the condensation temperature would be higher, again meaning that the
efficiency would
be lowered. If the turbine is at the bottom of the heat channel pipe, larger
quantities of
cold water could be used, the condensation temperature would be lower, and the

efficiency would be higher.
Consider an example. If the ocean surface temperature is 27 C., and the warm
water
cools by 2 as it provides heat to evaporate the heat transfer vapor, the
vapor would start
out at 25 C. By the time the vapor reached the bottom, the temperature might
be 35 C.
If the seawater temperature there is 4 and it warms up to 6 as it condenses
the working
fluid from the turbine, the condensation temperature would be 6 . The Carnot
efficiency
would be 9.4% (compared to 4.3% for conventional designs).
One thing that should be considered when the transfer fluid is compressed and
increases
in temperature is that it departs slightly from saturation properties. That
is, since it is
compressed adiabatically, its temperature is increased and it is in a
superheated state and
will not condense unless it contacts a surface that has a temperature below
its new
saturation temperature. In a specially designed heat exchanger, the
condensation of the
fluid releases the heat to boil the working fluid while the initial cool-down
energy could
be used to superheat the working fluid.

CA 02958456 2017-02-21
The movement of heat, which is accumulating at rate of .002 C per year
between depths
of 500 to 2000 meters compared to .01 degrees at the ocean surface is a
balancing of the
solar energy accumulating due to the greenhouse effect between the ocean
surface and
deep water where the heat produces less of an environmental impact.
A Simpler Design
Rather than having different fluids for the turbine working fluid and the heat
transfer
fluid, we can use the same fluid. This is illustrated in FIGURE 6. As in the
description
above, the heat transfer fluid 60 is boiled in evaporation tank 59 (or in a
multi-surface
heat exchanger) and flows down heat channel 61. At the bottom, it flows into
the turbine
64 to produce power. The exhaust from the turbine flows into condenser 65 and
is
condensed to a liquid. Feed Pump 68 pumps the liquid back to the evaporation
tank 56
(or a multi-surface heat exchanger) at the ocean surface to repeat the cycle.
The Carnot efficiency of this design is the same as the design of FIGURE 5,
but it would
probably be more efficient, since it eliminates a couple of heat exchangers.
There is
always some inefficiency in heat exchangers. The only reason for using the
more
complicated designs is that there may be some reason for using a different
fluid for the
turbine working fluid and for the heat transfer fluid.
Figure 6 also indicates heat rising from the condenser at a rate of 4
meters/yr back to the
ocean surface where in approximately 250 years it can be recycled into a heat
exchanger
to repeat the energy cycle.
The "Right-Side-Up" Ocean Power System
The description above was used to explain the principle, and it has some
thermodynamic
advantages. Most people involved with OTEC would prefer to have the turbines
and
generators at the surface of the ocean. FIGURE 7schematically shows how it
works.
warm seawater enters heat exchanger boiler 74 via pipe 72 and supplies heat to
boil the
working fluid, which then flows to the turbine 64. The warm ocean water exits
via pipe
73. Exhaust vapor from the turbine flows down the heat channel 61 to a
condenser 65 in
deep ocean. There it is condensed by cold ocean water entering by pipe 75. The

condensed liquid is then pumped back up to the heat exchanger 74 at the ocean
surface by
pump 76. The liquid is boiled in the heat exchanger boiler 74 and returned to
the turbine
again. The cold exhaust seawater is exhausted through pipe 77.
If desalination is desired, a separate evaporator at the ocean surface could
evaporate
seawater, and it could be condensed in a heat exchanger that evaporates some
heat
transfer fluid, which would then flow down the heat channel to be condensed by
cold
seawater.
Each 250 year cycle of global warming heat being returned to the turbine, to
the
condenser and back to surface again from a depth of1000 meters due to
diffusion
converts about 4 percent of the heat of global warming to productive work.
Water that

CA 02958456 2017-02-21
has arisen from 1000 meters can become new input water for the boiler. Once
greenhouse
gas emissions have stopped it would take about 6,250 (25x250 cycles) years to
convert
all of the heat that has gone into the oceans due to global warming to useful
work.
Figure 8 is a map of the world showing the five major ocean-wide gyres: the
North
Atlantic Gyre 81, South Atlantic Gyre 82, North Pacific Gyre 83, South Pacific
Gyre 84,
and Indian Ocean Gyre 85, which are large systems of circulating ocean
currents,
particularly those involved with large wind movements that are caused by the
Coriolis
effect. They do not occur at the equator, where the Coriolis effect is not
present. As
shown in Figure 1, solar radiation produces heat that flows from the equator
along the
ocean surface towards the pole. Since this flow is driven mainly by wind the
heat can
migrate rapidly towards the poles, where the must serious consequences of
global
warming are being manifested. As shown in Figure 4 the best locations for
producing
OTEC energy are within the 30 degree latitudes above and below the equator.
With the
OPS method ocean heat is located initially to a depth of 1,000, in which case
it cannot
reach the poles for at least 250 years and due to the ocean gyres the heat
that migrates
backs to the surface once it has diffuse back to the surface after 250 years
migrates back
towards the equator where it can become new input water for the boiler shown
in Figure
7 rather than migrating towards the pole. In this way the migration of surface
water
towards the pole is minimized and the best environmental result is produced by
the
balancing of trapped solar energy between the surface heat reservoir and the
deep cold
reservoir.
Advantages of the OPS Method
1. Higher efficiency.
2. Warm and cold Water do not have to be moved very far.
3. Cold Water does not have to be "dumped" near the ocean surface, which means
less
ecological effects.
4. Pipes are much smaller diameter.
5. Rather than having to pump 200 tons per second of cold water from one-
kilometer
depths, this method would require pumping about one ton of transfer fluid per
second to
produce 100 MW of power.
6. Rather than requiring 20% to 30% of the plant output to pump the water, it
might
require less than 10% to pump the transfer fluid.
7. The heat of global warming can be reduced to work, recycled and reused for
up to
6,250 years.

A single figure which represents the drawing illustrating the invention.

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Current owners on record shown in alphabetical order.
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BAIRD, JAMES R.
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